Differential Responses of Two Sorghum Genotypes to Drought Stress at Seedling Stage Revealed by Integrated Physiological and Transcriptional Analysis

Drought stress significantly limits crop growth and yield, and the mechanisms underlying genotypic variation in drought tolerance remain unclear. This study investigated the growth and transcriptomic responses of two sorghum varieties, drought-sensitive Jinza 35 (V1) and drought-tolerant Longza 24 (V2), under drought conditions. Comparative transcriptomic analysis, along with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, revealed distinct molecular mechanisms between the two varieties. Both varieties exhibited drought-responsive changes in photosynthesis-related pathways. However, the drought-tolerant V2 showed significant enrichment in phenylpropanoid biosynthesis, starch-sucrose metabolism, and plant hormone signaling pathways, suggesting enhanced metabolic flexibility under stress. In contrast, V1 primarily activated ribosome metabolism and cell cycle regulation pathways, indicating a less adaptive response focused on basic cellular processes. These findings highlight key metabolic and regulatory differences underlying drought tolerance in sorghum. The study provides valuable molecular insights and candidate pathways for future functional studies and the breeding of drought-resistant sorghum varieties.